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AN S-7600A/PIC16F877 JOURNEY

Part 3: Hot-Wiring the System
by Fred Eady

Start ı E-Mail 101 ı Automatic Transmission ı Mail Delivered ı Sources and PDF

AUTOMATIC TRANSMISSION

You donıt know it yet, but youıve graduated. You have a solid knowledge of how to send a simple e-mail by hand. To make the e-mail trick work on the S-7600A/PIC16F877 Internet Engine, all you have to do is a knowledge transfer.

From my previous articles, you already know about the S-7600A/PIC16F877 Internet Engine hardware and bootloader and how they work together. So, you can do a big GOTO in the source code you see in Listing 1.

Letıs start at the comment // SMTP code begins here. All of the code up to this point has been gathering information needed to connect, and then using that information to establish a PPP connection to my ISP. To connect to your ISP, simply put your ISPıs IP address in place of mine in the source code. The destination port is already set for 0x19, the well-known SMTP port. Your ISP phone number, log on ID, and password are prompted for in the beginning of the program.

Just like Photo 1, the first thing that should happen after a successful connection is the first 220 howdy message. Because Iım originating from a dial-up connection to ddi.digital.net, my HELO command contains an argument of ddi.digital.net. I only need to check the first four characters of any reply to know if things are good or bad. Actually, the first three would suffice, but it was a bit more logical for me to include the space following the reply to be absolutely sure I had parsed the reply code. One RFC says you can do it with a single character, and another tells you the space after the three digits is important. So, I took both RFCsı advice. I still check the first character, and I also look for the space.

Like the IP address, youıll need to change the MAIL and RCPT arguments to match your mailıs source and destination. By now, youıve got the idea. The PIC program is no more than a copy of the manual process I performed earlier. Only this time, the PIC is doing the keyboard work. All you have to do to get going for yourself is to literally fill in the blanks in Listing 1.

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